Field
This invention relates generally to a phased array antenna and, more particularly, to a phased array antenna for spacecraft and aircraft applications that uses a spatial combining technique employing beam scan phase shifters and true-time delay phase shifters so as to eliminate the need for a beam-forming network and intermediate frequency (IF) hardware and providing polarization control.
Discussion
Phased array antennas are well known in the art for many applications, where most phased array antennas include many antenna elements, such as 400 elements. The phase of each of the signals from a particular source that are received by the antenna elements are selectively controlled so that all of the signals are in phase with each at a common antenna port, which allows the antenna to be narrowly directed to the source with high gain. Typically, phased array antennas include beam-forming networks that weight the individual signals so as to adjust their amplitude and phase so that they can be coherently added together in this manner. Further, at relatively high frequencies, such as 40 GHz and above, beam-forming networks are not available and as such the received analog signals must be down-converted to an intermediate frequency signal before being sent to the beam-forming network, which requires significant hardware in each channel for the separate antenna elements. Also, known phased array antennas have limited flexibility because they are designed for a particular polarization. Thus, for space-borne applications, once the phased array antenna is launched on a satellite or spacecraft, it is not possible to change the polarization scheme for various types of communications signals.